Hitless protection for transmitting traffic in high-speed switching system

Abstract

A system to provide hitless protection includes a primary line card with a synchronous interface, the primary line card processing traffic with cells and encapsulating the traffic into synchronous frames in a predetermined format; and a back-up line card with a synchronous interface, the back-up line card processing the traffic with the cells and encapsulating the traffic into the synchronous frames in the predetermined format, wherein each line card includes a buffer to align the traffic before transmission, wherein the cell information sent by the primary line card is passed to the back-up line card, and wherein the back-up line card follows the received information to send to the destination cell.

What is claimed is: 
     
         1 . A system, comprising:
 a primary line card with a synchronous interface, the primary line card processing traffic with cells and encapsulating the traffic into synchronous frames in a predetermined format; and   a back-up line card with a synchronous interface, the back-up line card processing the traffic with the cells and encapsulating the traffic into the synchronous frames in the predetermined format, wherein each line card includes a buffer to align the traffic before transmission, wherein the cell information sent by the primary line card is passed to the back-up line card, and wherein the back-up line card follows the received information to send to the destination cell.   
     
     
         2 . The system of  claim 1 , wherein each cell comprises an independent frame. 
     
     
         3 . The system of  claim 2 , wherein the cell information comprises cell-to-frame mapping. 
     
     
         4 . The system of  claim 1 , wherein the cells are segmented by frame. 
     
     
         5 . The system of  claim 4 , wherein a cell size is a fraction of a frame size. 
     
     
         6 . The system of  claim 4 , wherein a cell size is larger than a frame size and wherein an end cell includes padding bytes. 
     
     
         7 . The system of  claim 1 , wherein each cell received by the line cards include a sequence number. 
     
     
         8 . The system of  claim 7 , comprising an alignment buffer is organized by the sequence number. 
     
     
         9 . The system of  claim 7 , wherein the sequence number is allocated for each flow. 
     
     
         10 . The system of  claim 7 , wherein information from the primary line card to the back-up line card includes a sequence number. 
     
     
         11 . The system of  claim 1 , wherein information from the primary line card to the back-up line card includes flow identification. 
     
     
         12 . The system of  claim 11 , wherein the traffic comprises an Optical Transport Network (OTN) where one flow comprises an Optical channel Data Unit (ODU) slot. 
     
     
         13 . The system of  claim 11 , wherein information for each flow is transmitted through dedicated signal(s). 
     
     
         14 . The system of  claim 11 , wherein signals from the primary line card to the back-up line card are shared among different flows. 
     
     
         15 . The system of  claim 1 , wherein information from the primary line card to the back-up line card is passed to the back-up line card in each frame. 
     
     
         16 . The system of  claim 15 , wherein information is transmitted based on a cycle from a sync signal or is transmitted once every predetermined frame cycles. 
     
     
         17 . The system of  claim 15 , wherein information transmission is delayed for a plurality of cycles after a sync signal. 
     
     
         18 . The system of  claim 1 , comprising a sync signal synchronous to a frame start used by both line cards. 
     
     
         19 . The system of  claim 18 , wherein information is transmitted based on a cycle from the sync signal or is transmitted once every predetermined frame cycles. 
     
     
         20 . The system of  claim 18 , wherein information transmission is delayed for a plurality of cycles after a sync signal. 
     
     
         21 . The system of  claim 1 , wherein the primary line card delays the traffic transmission for a plurality of cell cycles to compensate for switching delay and jitter. 
     
     
         22 . The system of  claim 1 , wherein the synchronous interface comprises an optical transport network. 
     
     
         23 . The system of  claim 1 , wherein the frames are sent using time-division multiplexing (TDM) or packet switching. 
     
     
         24 . The system of  claim 23 , wherein the cell includes a sequence number and a flow identification with different length for TDM and packet switching. 
     
     
         25 . The system of  claim 23 , wherein the cell includes a sequence number and a flow identification with different length for TDM and packet switching. 
     
     
         26 . The system of  claim 1 , comprising a frame-synchronous sync signal to enable sending of cell information for the backup line card to apply the information to a predetermined frame.